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By Brandon Speedie Wii Nunchuk RGB Light Driver Add fun to a party or a professional look to a live performance with this RGB strip lighting driver. It is motion operated through an inexpensive video game controller and includes a built-in strobe light. T he Nintendo Wii is unusual for video game consoles as it uses gestures for control. The input device has buttons like a traditional controller plus a built-in accelerometer. For example, you can hold the controller like a racquet and make a motion to hit a ball for a tennis game. The “Nunchuk” is an attachment for the main Wii controller that includes buttons and a joystick. It is a convenient input device for this project as it communicates via the standard I2C two-wire serial interface, so it can easily be interfaced with a microcontroller. Also, the plug is a perfect fit for a standard 1.6mm-thick PCB, so a connector can be made from the PCB itself, without the need for a proprietary component. There are inexpensive grey-market clones readily available, including UHF wireless versions for cable-free operation. Gestures This project is intended to control four strips of 12V RGB (red/green/ blue) strip lighting, as well as an array of PCB-mounted white LEDs for strobing. Each colour in the RGB strip is independently controlled by pulsewidth modulation (PWM), so we can make any colour or brightnesses we RGB Light Driver Features » Drives up to four independent RGB LED strips » Optional onboard white LED strobe » Functions include variable stripe colour & brightness, strobing, sweeping & fading » Random sequence function » Controlled via a Wii Nunchuk controller (wired or wireless) » Powered from 12V DC 66 Silicon Chip Australia's electronics magazine fancy. Each strip can also be turned on or off as a group, providing further flexibility. The PCB-mounted white LEDs have a simple on/off control to act like a strobe light. We therefore have control of the RGB strip colour, RGB strip brightness, strip on/off and strobe on/off. The controller has two buttons, a joystick, and a three-axis accelerometer, with the axes shown in Fig.1. We therefore have the following inputs: • Joystick X-axis position (8 bits) • Joystick Y-axis position (8 bits) • X-axis (left/right) acceleration (10 bits) • Y-axis (forward/backward) acceleration (10 bits) • Z-axis (up/down) acceleration (10 bits) • C (small) button on/off • Z (big) button on/off The angle of the joystick controls the colour. Right (east) is red, down to the left (southwest) is green, and up to the left (northwest) is blue. Anything between these positions will be a mix of the two nearest colours (see Fig.3). siliconchip.com.au Y X Z a 10% duty cycle (on for 10ms, off for 90ms, repeating at 10Hz). X-axis acceleration triggers a different type of strobing called ‘channel sweep’. If the controller is shaken left and right, individual strips are cycled on and off sequentially. The individual on-time is 100ms, so it takes 400ms to cycle through all four strips. Y-axis acceleration triggers an automatic fade from full brightness to off. A sharp thrust forward starts the effect, which takes around two seconds. The lights will stay off until the joystick is returned to the centre position. Circuit details Fig.1: the Nunchuk remote used to control the LED strips. The acceleration of the joystick Z-axis (up/ down) controls brightness, the X-axis (left/right) triggers the channel sweep and the Y-axis (forward/backwards) triggers the brightness fade. Brightness is derived from a mixture of inputs; firstly, the position of the joystick. When in the centre position, the lights are off. As the joystick is pushed in any direction, the brightness increases until it is pressed fully against a side limit, at which point we have half brightness. The other half of the brightness signal comes from the Z-axis acceleration. By gesturing up and down, the brightness is throttled. The lights can therefore be ‘played’ like a drum to intuitively match the rhythm of music or the tempo of a performance. The Z button also affects brightness. When held down, the Z-axis acceleration is ignored and the brightness is solely controlled by the joystick ‘magnitude’. This can be used to force full brightness instantly, but also for producing a subtle, steady colour without having to hold the controller stationary. The C button controls the strobe. When held down, the strip LEDs are driven on (white) at full brightness, along with the PCB-mounted white LEDs. The flash period is 100ms with siliconchip.com.au The circuit is shown in Fig.2; the brain of the operation is IC2, a Microchip (previously Atmel) ATmega32U4 microcontroller programmed as an Arduino Leonardo. In-circuit serial programming (ICSP) header CON2 and JTAG header CON3 are provided for programming it. The Nunchuk controller connects to PCB card-edge connector (CON102), which supplies 3.3V power to the controller and connects the two I2C communications lines, SDA (data) and SCL (clock). These are connected directly to the dedicated peripheral in the microcontroller. I2C is an open-drain bus, so 4.7kW pullup resistors are provided, although experience suggests there are internal pullups in the Nunchuk, so they are not strictly necessary. Series protection resistors are provided but are usually fitted as 0W links. Higher values could be used to provide some protection to the processor should the Nunchuk ever be extended to a long cable run, but I haven’t found it to be necessary. Footprints for two different external clock sources are provided. I used ceramic resonator X1, but there is also provision for a 5×3.2mm SMD crystal, X2, with the two necessary load capacitors. The microcontroller runs at 16MHz, which is a bit overclocked for 3.3V operation (the data sheet suggests a 4.5-5.5V supply for that clock rate). Still, given that we aren’t using any of the chip’s analog features, it shouldn’t be a problem. USB-C connector CON5 provides an interface for uploading firmware and a generic serial port for debugging etc. Capacitive touch button S1 is made Australia's electronics magazine from a large copper area on the PCB. Pressing the area with a finger cycles through program ‘modes’, to be discussed later. LEDs 8, 9, 12, 17, 21 & 22 are reverse-entry LEDs ‘charlieplexed’ to indicate to the user which mode they are in. Charlieplexing is a technique that we described in some detail in the September 2010 issue (siliconchip.au/ Article/287). It allows multiple LEDs to be driven by a minimal number of pins that can be tri-stated; in this case, only three pins and resistors are required to light any one of six LEDs. The strip LED connectors are fourway header sockets, with pairs connected in parallel. This gives flexibility to suit different strips (for example, to fit male and female connectors) or simply to give more outputs to drive more LED strips. Note that most strips have connectors on both ends, so they can also be extended in series. Strip LEDs are typically constructed with a common anode pin and individual cathode pins for each of the three colours: red, green, and blue. To light a colour, we need to supply +12V DC to the anode and 0V DC to whichever cathode we want to light up at full brightness. On the strip, power flows from the anode terminal through a current-­ limiting resistor and a string of three LEDs in series before exiting the cathode terminal. High-side P-channel Mosfets Q1, Q2, Q3 and Q13 control the +12V drive to the anode terminals. On startup, they are held off courtesy of 4.7kW gate pullup resistors. Logic-level N-channel Mosfets Q4, Q5, Q6 & Q14 are connected to the microcontroller through 470W gate drive resistors. When their gates are driven high (to 3.3V), they conduct and pull the gate of their corresponding high side Mosfet low, which in turn supplies +12V to the strip. The strip cathodes are also connected to six N-channel Mosfets, Q7-Q12. Their gates also connect to the microcontroller through 470W gate resistors. These gates are PWM-driven to provide a full colour palette. PCB-mounted white LEDs101LED136 feature three separate dies in a single package. There are 35 in total, with 17 on one side and 18 on the other, as there is no LED134. The three LEDs in each package are March 2024  67 +12V +12V REG1 ZLDO1117G33TA D1 GS1G K A + GN D 10 m F – VCC (3.3V) VCC (3.3V) OU T IN 22 m F 1 0 0 nF 1 0 0 nF CON1 44 24 2 +3.3V 4 .7 k W C O N102 NUNCHUCK AVcc AVcc Vcc Vcc UVcc TD1/PF7 TD0/PF6 19 18 TMS/PF5 SDA SCL TCK/PF4 0W ADC0/PF0 1 MW CON5 USB-C ADC1/PF1 PD6/ADC9 ADC11/PB4 PD4/ADC8 INT6/AN0/PE6 ADC10/PD7 IC2 ATMega32U4 0W 7 22 W 4 3 22 W 22 LED23 ADC13/PB6 VBUS OC3A/P6 D+ ADC12/PB5 D– PD2/RXD1 PD3/TXD1 PD5/XCK1 SS/PCINT0 470 W PF6 37 38 PF5 39 PF4 X2 16MHz 42 X1 1 6 M Hz 6 5 ALTERNATIVES SCLK XTALI MOSI A re f MISO Ucap RESET UGND /HWB 15 1mF GND 23 GND 470 W 43 K LED17 A K A l K K l A K l A 4.7kW LED12 AUDIO_IN 4 70 W ENABLE1 4 70 W ENABLE2 28 470 W ENABLE3 1 470 W ENABLE4 27 470 W RED1 12 470 W GREEN1 32 470 W BLUE1 30 31 29 470 W RED2 20 470 W GREEN2 21 470 W BLUE2 8 STROBE AUDIO_IN JTAG 2 GND PF6 3 4 VCC PF5 5 6 VTG 7 8 PF7 9 10 C O N3 RST 0W* GND VCC 9 SCK * NOT NORMALLY FITTED 10 MOSI 11 MISO AVR ICSP 13 MISO 1 33 GND 35 LED21 l VCC GND 1 0 0 nF l 40 XTAL2 1MW 17 A A 41 l 16 l LED8 PF4 1 22pF 22pF CLK0/PC7 PF7 XBEE_TX 5.1kW 5.1kW 0C0A/PB7 36 K LED9 470 W 470 W G2 G1 A1 B12 A2 B11 A3 B10 A4 B9 A5 B8 A6 B7 A7 B6 A8 B5 A9 B4 A10 B3 A11 B2 A12 B1 26 25 CAPACITIVE BUTTON 100nF 34 14 4.7kW 0W LED22 MIDI, XBEE_RX 12V IN P U T 470 W 2 VCC SCK 3 4 MOSI 5 6 GND RST 4 .7 k W CON2 MISO 12 CTS 11 GND LED7 A 9 10 8 7 6 5 3 4 l 2 470W LED5 OPTO5 TLP290 MIDI A DTR NC PWM1 RSSI RESET DIO12 DIN VCC DOUT 470W 470W 470W XBEE 3 RF MODULE 1 VCC VCC DIO4 13 14 NC ON 15 16 RTS ASSOC. 18 17 AD3 AD2 20 AD1 AD0 MOD1 19 MOSI l K l 1 4 A LED6 CON7 4 3 K XBEE_TX MIDI IN 2 l K 1 2 5 3 R78 XBEE_RX VCC VCC SC Ó2024 VCC NUNCHUCK LIGHTS CONTROLLER Fig.2: the most important parts of the circuit are microcontroller IC2 and the Mosfets it uses to drive the RGB LED strips (connected via the headers at upper right) plus the white ‘strobe’ LEDs shown on the right. The faded-out components are for future expansion and not needed for the features described here. 68 Silicon Chip Australia's electronics magazine siliconchip.com.au +12V +12V 4.7kW Q4 BSS138 Q1 IRFR9010 S G D D ENABLE1 G 4.7kW Q6 BSS138 S G D D ENABLE2 G S Q3 IRFR9010 4 .7 k W Q5 BSS138 S G D ENABLE3 D G S Q2 IRFR9010 4 .7 k W Q14 BSS138 G D Q 13 IRFR9010 D ENABLE4 G S S S ENABLE2 ENABLE3 RED1 Q8 G G G Q 7 ,Q 8 ,Q 9 , Q10,Q11,Q12: MC U 3 0 N 0 2 Q7 G TO LED138 TO LED134 TO LED139 Q11 S LED1, LED2, LED3 & LED4 D D Q9 D S BLUE1 TO LED4 D D GREEN1 TO LED137 TO LED2 TO LED3 TO LED1 ENABLE4 S G G l l l l l l KB LED134, LED137, LED138,LED139 S RED2 GREEN2 l KG Q 10 S l KR D S A Q 12 l RED2 BLUE2 GREEN2 BLUE2 STROBE l l l l l l l l l VCC A KR R73 KG IC3: LMV324 KB 5 6 1mF IC3b 7 VCC/2 LED101 – LED136 (18 TOTAL) R72 K l A K l A K l A K l A K l A K l A +12V D STROBE 470 W G AUDIO_IN Q 16 MCU30N02 S 4 .7 k W 10 NOTE: FADED COMPONENTS WERE NOT INSTALLED ON PROTOTYPE AND ARE NOT REQUIRED. 9 IC3c 8 LED102 – LED135 (17 TOTAL) R60 K l A K l A K l A K l A K l A K l A D 12 14 R61 K LED18 l LED19 l G 13 Q 15 MCU30N02 S 4 .7 k W 1mF R64 LED20 A A LED15 l K K A A l 470 W +12V +12V VCC VCC K K l R63 A A A l R62 IC3d STROBE LED13 K l LED16 R65 1mF 4 AUDIO_RAW 1 LED14 R81 S1 ELECTRET MIC 2 11 K R80 R79 1mF A l 3 IC3a 1mF LED11 VR100 10kW 1MW CON100 K A l K siliconchip.com.au R70 LED10 CON101 VCC/2 Australia's electronics magazine March 2024  69 wired in series, with the combined LEDs connected in two parallel sets to +12V through 6.2W current limiting resistors. To light them up, N-channel Mosfets Q15 & Q16 are driven into conduction through 470W gate drive resistors by the microcontroller. 4.7kW pull-down resistors ensure the LEDs are off even if the microcontroller is not programmed or running, and therefore has its I/O pins at a high impedance. LDO regulator REG1 (ZLDO1117) creates the 3.3V supply for the microcontroller and Nunchuk from the incoming 12V. REG1 will work with ceramic capacitors, unlike many other linear regulators that need some ESR in their output capacitor to ensure stability, mandating an electrolytic type. Diode D1 provides reverse-­ polarity protection. It is expected that the 12V DC will be supplied by an off-board caged type SMPS or power brick derived from the mains. For four LED strips, 48W (4A) should be plenty, though I used 100W (8.3A) as I had such a supply on hand and it gives me the flexibility to use more strips if I want. I have also directly used 12V DC from a lead-acid battery and solar panel at a music festival where AC mains power was not available. Firmware operation Much of the heavy lifting involved in setting up the I2C peripheral and communicating with the Nunchuk is handled by the ArduinoWirelessNunchuk library. Once the object is set up, all we need to do is call nunchuck. update() to read the controller. The joystick position is stored in 8-bit variables nunchuck.analogX and nunchuck.analogY, giving a range of 0 (left/down) to 255 (up/right). The values sit around 127 if the joystick is centred. These Cartesian coordinates are not that useful to us; what we really want Fig.3: this shows how the ConvertToRGB() function converts the joystick position to a colour in one of six ‘bins’. is an angle (for colour) and a magnitude (for brightness). So the first thing we do is subtract 127 from each reading to give a centre position of 0 and positive numbers for up/right and negative for left/down. Then we convert to polar coordinates using √(x2 + y2) for the distance from the centre and arctangent for the angle: uint8_t magnitude = sqrt( sq(x_normalised) + sq(y_normalised)); int16_t angle = round(atan2( y_normalised, x_normalised) * 180 / 3.14159265); The magnitude is then summed with the z-axis acceleration to give a final brightness figure between 0 and 255. If the Z button is being held down, we double the magnitude value rather than summing it with the Z-axis acceleration. We now have our colour defined in the HSB (hue, saturation, brightness) colour system. Hue is our joystick angle, brightness is our joystick magnitude + z acceleration, and saturation is hard coded to its maximum for the most vibrant colour. We then Table 1 – hue ‘bins’ (b = brightness, h = hue[°] ÷ 60) Bin # Hue range Red (0-255) Green (0-255) Blue (0-255) 0 0-59° b b×h 0 1 60-119° b × (2 – h) b 0 2 120-179° 0 b b × (h – 2) 3 180-239° 0 b × (4 – h) b 4 240-299° b × (h – 4) 0 b 5 300-359° b 0 b × (6 – h) 70 Silicon Chip Australia's electronics magazine convert to the RGB colour space using convertRGB(), which works by segregating the brightness into one of six ‘bins’ based on hue. Each bin is selected as hue(°) ÷ 60 to give a full colour wheel (see Fig.3). With saturation at maximum, the six bins are calculated as per Table 1. These red, green and blue magnitudes are then used to update the PWM outputs. This firmware uses the Arduino’s built-in analogWrite() function, which provides 8-bit resolution at 490Hz. For the strobe, it looks at the status of the boolean (true/false) variable nunchuck.cButton. If true, the c button is being pressed. Variables to control the on and off time of the strobe are loaded with the current time, plus a user-configurable offset: strobe_on = now + STROBE_DUTY; strobe_off = now + STROBE_ DURATION; By default, STROBE_DUTY is 10 milliseconds and STROBE_DURATION is 100 milliseconds, although they can easily be changed to suit the application. If the current time (“now”) is less than strobe_on, the strip LEDs are driven to full brightness on all three colours, giving a bright white. The PCB-mounted white LEDs are also switched on. If the current time is greater than strobe_on, we are in the off period between flashes, so all outputs are driven low. If the present time exceeds strobe_off, the off-period has elapsed, and we need to begin the cycle again. Variables strobe_on and strobe_off are loaded with new values and the flash repeats. Channel sweep works similarly. If the X-axis acceleration (left/right) value is below X_THRESHOLD (default 20), we know the controller is being shaken vigorously. The ‘resting’ value is 512 (around half the 10-bit limit of 1023), so 20 corresponds to a high acceleration in the negative direction of the axis. The time when that threshold is crossed is stored in memory, and the channel sweep starts. The current time is then compared with the previously saved time, and if the difference is more than CHANNEL_SWEEP_PERIOD (default 100ms), we know to cycle to the next LED strip. Channel sweeping works by turning off all but one of the siliconchip.com.au high-side Mosfets that feed the LED strips with +12V. By turning these on or off sequentially, a visually appealing strobing effect is achieved. Similarly, the automatic fade works by checking if the Y-axis acceleration (forward/backward) is below Y_THRESHOLD (default 20). If the controller is thrust forward sharply, this limit will be exceeded and the brightness will subsequently be set to maximum. For the fade program cycle, the brightness is then decremented by FADE_STEP (default 5) until it reaches zero. This achieves a fade from full brightness to black in around two seconds. The lights will stay off until the joystick returns to the centre position, at which point colour_sweep_retrigger is unlatched and normal operation resumes. The firmware also supports an automatic mode. The LED strips will go through a random sequence without user input. The mode is cycled using the capacitive touch button. A square wave is applied to this pad by a pin on the microcontroller. A separate pin senses the voltage on the copper pad. The time it takes to charge and discharge this copper area is proportional to the capacitance of the pad, which changes if a finger touches it. That is sensed in the software as a button touch, which cycles through modes. For more on how that works, see my March 2015 article on an Arduino Touch Shield (siliconchip.au/ Article/8386). The current mode is indicated via the reverse-entry LEDs LED21 & LED22. Only those two are currently driven by the firmware, although six are provided for future expansion. Three pins drive the Charlieplexed LED array. In auto mode, the brightness and hue are randomly generated through Arduino’s built-in pseudo-random number generator function, random(). Once a new random value is calculated, the current brightness and hue will slowly ramp towards those values. When it reaches them, new numbers are generated. This gives a continuously variable LED brightness and colour. Construction Begin by soldering all components to the PCB, referring to the overlay siliconchip.com.au Parts List – RGB Strip Lighting Driver 1 double-sided PCB with black solder mask coded 16103241, 213 × 158mm 1 220 × 160 × 80mm ABS plastic enclosure [Altronics H0313 or H0333] 1 high-current 12V DC power supply 1-4 RGB LED strips [Altronics X3213A or X3328] 1 Wii Nunchuk or compatible controller, wired or wireless 1 16MHz 3-pin SMD ceramic resonator, 3.2 × 1.3mm (X1) [CSTNE16M0V530000R0] 1 2-way 10A+ 5/5.08mm pitch terminal block (CON1) 1 3×2 pin header (CON2; optional, for in-circuit programming of IC2) 1 5×2 pin header (CON3; optional, for JTAG programming/debugging of IC2) 1 Molex 2171790001 16-pin USB Type-C connector (CON5) 4 4-pin right-angle headers, 2.54mm pitch (LED1, LED2, LED138, LED139) Semiconductors 1 ATmega32U4 8-bit micro programmed with 1610324A.HEX, TQFP-44 (IC2) 1 ZLDO1117G33TA 3.3V 1A low-dropout regulator, SOT-223 (REG1) 4 IRFR9010 50V 5.3A P-channel Mosfets, TO-252/DPAK (Q1-Q3, Q13) 4 BSS138 50V 220mA N-channel Mosfets, SOT-23 (Q4-Q6, Q14) 8 MCU30N02 20V 30A N-channel Mosfets, TO-252/DPAK (Q7-Q12, Q15, Q16) 3 green SMD LEDs, M3216/1206/SMA size (LED21-LED23) 35 Cree CLP6B-WKW-CD0E0233 cool white LEDs, PLCC-6 (LED101-LED136) 1 GS1G 400V 1A diode, SMA/DO-214AC (D1) Capacitors (all SMD M2012/0805 size unless noted) 1 22μF 25V X5R M3216/1206 size 1 10μF 50V X5R M3216/1206 size 1 1μF 50V X7R 4 100nF 50V X7R Resistors (all SMD M2012/0805 size 1% unless noted) 1 1MW 2 5.1kW 9 4.7kW 17 470W 2 22W 35 6.2W 1W M6332/2512 [eg, Panasonic ERJ1TRQF6R2U] 4 0W diagrams, Figs.4 & 5. The double-sided board used is coded 16103241 and measures 213 × 158mm. There are components on both sides, although most mount on what will become the underside. Quite a few components are for future expansion and were missing from our prototype, so we suggest you leave them off too. They are shown faded out (transparent) in Figs.4 & 5 and are not in the parts list. As a general rule, start with the lowest profile SMD parts and work up to the larger through-hole components. All can be soldered by hand, but a reflow oven and solder paste can also be used for the SMD components if that is your preference. For those who haven’t tried it, a hot plate also works surprisingly well. It may sound crude, but laying your PCB into a foil-covered pan on the stove is very effective. For many years, I have used a standalone electric hot plate for this purpose, and it has been well worth the $20 investment. Fit all the SMDs on the bottom side first. If soldering by hand, start with IC2 by applying flux paste and then Australia's electronics magazine dragging a tinned chisel tip across the quad flat pack pins. The larger SMD components, such as power Mosfets Q1, Q3 etc and low-dropout regulator REG1, are easiest done next by applying a small amount of solder to the large copper area and leaving the iron to heat the area for several seconds. The component can then be placed using tweezers. Ceramic resonator X1 can be mounted similarly; all three pads can be heated simultaneously. Next, solder all passives. All resistors and capacitors are M2012/0805 size (2.0 × 1.2mm) or larger, so they are manageable by hand. I prefer to first wet one pad with solder, place the component with tweezers, then solder the other pad once the first has set and the component is held in place. Finish the SMD parts by soldering the SOT-23 transistors, diode D1 and the reverse-entry LEDs. Note that the LEDs must face down; they shine through holes in the PCB. Now flip the PCB over and solder the 6-pin PLCC strobe LEDs. This is a challenging component to solder due March 2024  71 Figs.4 & 5: most of the parts are mounted on what will become the underside of the PCB (inside the case). The PCB is attached to the case like a lid, so only the components on the top, including most of the connectors and the capacitive button, are externally accessible. Note how the LEDs all mount on the bottom side but they shine through holes in the board so they’re visible from the top. The 0W resistor (labelled in red) connected to CON3 is only fitted if you want the reset line to also pull down the test reset, for this application it does not need to be fitted. 72 Silicon Chip Australia's electronics magazine siliconchip.com.au This is the side of the board that’s externally visible when mounted in the case. This overlay shows all 35 white LEDs fitted; if you don’t need the strobe to be super bright, you could install a subset of those. I included the 17 evennumbered white LEDs on my prototype and it was bright enough for me. siliconchip.com.au Australia's electronics magazine March 2024  73 to its high thermal mass. If your soldering iron has an adjustable temperature, I recommend you turn it up to at least 400°C, then work your way along the six leads individually. The solder must flow down the leg onto the pad, so apply heat for several seconds to ensure proper wetting. Finish the PCB by soldering the through-hole components: the LED strip headers and screw terminals. If you are planning on modifying the firmware, install USB-C connector CON5. Start with the through-hole pins that hold it in position, then solder the SMD signal pads using the same drag method as for IC2. Power supply We recommend using an external 12V DC ‘brick’ supply since that’s the safest and easiest option. You don’t need to do any mains wiring. All you need to do is wire up its output (with the correct polarity!) to CON1. As we’ve recommended that you fit CON1 on the underside of the board, you can drill a hole in the side of the box and run the wire in through a grommet and directly into the terminals of CON1. You could use a chassis-­mount DC socket and plug, but watch the current ratings of the wiring, socket and plug to ensure they can handle the full output of your supply. While it’s possible to install a mains to 12V DC switch-mode power supply in the base of the box (using a metal baseplate like Altronics’ HA0312A that suits the specified cases), we won’t explain how to do that. You would need to be careful to anchor the mains cable (or use a socket), use mains-rated wiring and plenty of insulation and cable ties to keep it safe. For portable use, one good battery option is to use Makita 12V lithium-­ ion battery packs. They are readily available at hardware stores; you can keep a few charged ones with you while you’re on the go. You can also use them with their power tools! I got the socket from AliExpress for $15 (siliconchip.au/link/abrh), and it works well. Now you can attach the PCB to the top of the enclosure. It takes the place of the enclosure lid in this design and is attached using the screws that come with the case. Finishing it off & using it If you got your microcontroller from the Silicon Chip Online Shop, it will already be programmed. However, if you used a blank chip, you will need to flash the Arduino bootloader onto it via ICSP header CON2 or JTAG header CON3, using a hardware programmer. If you don’t have a hardware programmer, some low-cost options are: • Duinotech ISP Programmer (Jaycar XC4627, $14.95) This is an early prototype, so I had to make some modifications, including rerouting a couple of tracks. The final version of the board presented here won’t require those changes. 74 Silicon Chip Australia's electronics magazine siliconchip.com.au • Pololu USB AVR Programmer v2.1 (Core Electronics [CE] POLOLU-3172, $26.05) • SparkFun Tiny AVR Programmer (CE PGM-11801, $33.32) • SparkFun Pocket AVR Programmer (CE PGM-09825, $33.25) • USBasp USBISP AVR Programmer (CE 018-USB-AVR-ISP, $10.95) If you have a spare Arduino, you can repurpose it as a hardware programmer using the “Arduino ISP” project – see siliconchip.au/link/abri Make sure the Leonardo is selected in Tools → Board and select your programmer from Tools → Programmer. You may also need to select the serial port for the programmer. Then use Tools → Burn Bootloader to turn the blank chip into a Leonardo. Our article on repairing an Uno goes into more detail on ISP programming the processor on an Arduino board (March 2020 issue; siliconchip.au/ Article/12566). Once flashed, the microcontroller should automatically appear as a virtual serial port when plugged into a computer via the onboard USB port. If not, drivers can be manually downloaded and installed from the Arduino website (siliconchip.au/link/abrj). Once you have that working, the firmware can then be uploaded via the USB port using the Arduino IDE. You should now have a functioning product. Plug your Nunchuk controller into the PCB, ensuring the connector is orientated correctly (notch facing up) – see Fig.6. Plug in your RGB LED strip(s), and you should be ready to perform! A bit of practice is required to get familiar with the controls, but before long, it begins to feel natural. Once comfortable with the basics, you will find yourself combining multiple controls to give a more compelling experience. Experience suggests the Z button works well with the channel sweep, Fig.6: the correct orientation for the Nunchuk controller plugged into the PCB connector. Note how the notch is facing up. and sparing use of the C (small) button in combination with the Z-axis acceleration to add interest. A final word of advice: much like the rest or pause in music, sometimes periods of darkness can add emphasis. SC Less is more! I only fitted the white strobe LEDs on one side of the board, but you will get a brighter strobe if you add them on both sides. The board name was also changed to a slightly less ‘silly’ one during development. siliconchip.com.au Australia's electronics magazine March 2024  75